After he turned Lutheran and later Calvinist, he was forced into exile for many years, with stays in Basel, Geneva, Tübingen, Strasbourg, Besançon, and elsewhere.
His remarkable erudition and breadth of view had a considerable effect on the subsequent development of French law.
At the same time, several of this works stirred considerable controversy, and some were condemned by Lutherans, Calvinists and/or Catholics for religious reasons.
[3] Dumoulin was a bitter enemy of feudalism, which he attacked in his De Feudis (Paris, 1539).
In 1559, he published an edition of the Decretum Gratiani; in the commentaries, he pointed out spurious materials contained in this important collection of canon law.